1. Field of the Invention
The present invention relates to microbial pectate lyases, more specifically to microbial enzymes exhibiting pectate lyase activity as their major enzymatic activity in the neutral and alkaline pH ranges; to a method of producing such enzymes; and to methods for using such enzymes in the textile, detergent and cellulose fiber processing industries.
2. Description of Related Art
Pectin polymers are important constituents of plant cell walls. Pectin is a hetero-polysaccharide with a backbone composed of alternating homogalacturonan (smooth regions) and rhamnogalacturonan (hairy regions). The smooth regions are linear polymers of 1,4-linked alpha-D-galacturonic acid. The galacturonic acid residues can be methyl-esterified on the carboxyl group to a varying degree, usually in a non-random fashion with blocks of polygalacturonic acid being completely methyl-esterified.
Pectinases can be classified according to their preferential substrate, highly methyl-esterified pectin or low methyl-esterified pectin and polygalacturonic acid (pectate), and their reaction mechanism, beta-elimination or hydrolysis. Pectinases can be mainly endo-acting, cutting the polymer at random sites within the chain to give a mixture of oligomers, or they may be exo-acting, attacking from one end of the polymer and producing monomers or dimers. Several pectinase activities acting on the smooth regions of pectin are included in the classification of enzymes provided by the Enzyme Nomenclature (1992) such as pectate lyase (EC 4.2.2.2), pectin lyase (EC 4.2.2.10), polygalacturonase (EC 3.2.1.15), exo-polygalacturonase (EC 3.2.1.67), exo-polygalacturonate lyase (EC 4.2.2.9) and exo-poly-alpha-galacturonosidase (EC 3.2.1.82).
Pectate lyases have been cloned from different bacterial genera such as Erwinia, Pseudomonas, Klebsiella and Xanthomonas. Also from Bacillus subtilis (Nasser et al. (1993) FEBS 335:319-326) and Bacillus sp. YA-14 (Kim et al. (1994) Biosci. Biotech. Biochem. 58:947-949) cloning of a pectate lyase has been described. Purification of pectate lyases with maximum activity in the pH range of 8-10 produced by Bacillus pumilus (Dave and Vaughn (1971) J. Bacteriol. 108:166-174), B. polymyxa (Nagel and Vaughn (1961) Arch. Biochem. Biophys. 93:344-352), B. stearothermophilus (Karbassi and Vaughn (1980) Can. J. Microbiol. 26:377-384), Bacillus sp. (Hasegawa and Nagel (1966) J. Food Sci. 31:838-845) and Bacillus sp. RK9 (Kelly and Fogarty (1978) Can. J. Microbiol. 24:1164-1172) has been reported, however, no publication was found on cloning of pectate lyase encoding genes from these organisms. All the pectate lyases described require divalent cations for maximum activity, calcium ions being the most stimulatory.
WO 98/45393 discloses detergent compositions containing protopectinase with remarkable detergency agains muddy soilings.
Generally, pectinase producing microorganisms exhibit a broad range of pectin degrading or modifying enzymes. Often the microorganisms also produce cellulases and/or hemicellulases and complex multi-component enzyme preparations from such microorganisms may be difficult to optimize for various applications, they even may contain enzymes with detrimental effect. Thus, it is an object of the present invention to provide a pectin degrading enzyme exhibiting only the desired effects e.g. in detergents or different industrial processes.
The inventors have now found and identified several novel enzymes having substantial pectate lyase activity which perform excellent in various industrial process under neutral or alkaline conditions and have succeeded in identifying DNA sequences encoding such enzymes, these enzymes forming a novel class of pectate lyases having at least conserved region with identical partial amino acid sequence.
Accordingly, in a first aspect this invention relates to a pectate lyase comprising a first amino acid sequence consisting of seven (7) amino acid residues having the following sequence: Asn Leu Asn Ser Arg Val Pro (NLNSRVP) (SEQ ID NO: 2). In further embodiments, the pectate lyase may additionally hold a second amino acid sequence consisting of six (6) amino acid residues selected from the group consisting of the sequences Trp Val Asp His Asn Glu (WVDHNE) (SEQ ID NO: 4) and Trp Ile Asp His Asn Glu (WIDHNE) (SEQ ID NO: 2); and optionally also a third amino acid sequence consisting of three (3) amino acid residues having the following sequence: Ser Trp Asn (SWN).
The DNA sequences of five pectate lyases of the invention are listed in the sequence listing as SEQ ID NOS: 1, 3, 5, 7 and 9, respectively, and the deduced amino acid sequences are listed in the sequence listing as SEQ ID NOS: 2, 4, 6, 8 and 10, respectively. It is believed that the novel enzyme will be classified according to the Enzyme Nomenclature in the Enzyme Class EC 4.2.2.2. However, it should be noted that the enzyme of the invention also exhibits catalytic activity on pectin (which may be esterified) besides the activity on pectate and polygalacturonides conventionally attributed to enzymes belonging to EC 4.2.2.2.
In a second aspect, the present invention relates to a pectate lyase which is i) a polypeptide produced by Bacillus agaradhaerens, NCIMB 40482 or DSM 8721, or ii) a polypeptide comprising an amino acid sequence as shown in positions 27-359 of SEQ ID NO: 2, or iii) an analogue of the polypeptide defined in i) or ii) which is at least 45% homologous with said polypeptide, or iv) is derived from said polypeptide by substitution, deletion or addition of one or several amino acids, provided that the arginine in position 240, and optionally also the arginine in position 245, is conserved and the derived polypeptide is at least 42% homologous with said polypeptide, or v) is immunologically reactive with a polyclonal antibody raised against said polypeptide in purified form.
Within one aspect, the present invention provides an isolated polynucleotide molecule selected from the group consisting of (a) polynucleotide molecules encoding a polypeptide having pectate lyase activity and comprising a sequence of nucleotides as shown in SEQ ID NO: 1 from nucleotide 79 to nucleotide 1077; (b) species homologs of (a); (c) polynucleotide molecules that encode a polypeptide having pectate lyase activity that is at least 45% identical to the amino acid sequence of SEQ ID NO: 2 from amino acid residue 27 to amino acid residue 359; (d) molecules complementary to (a), (b) or (c); and (e) degenerate nucleotide sequences of (a), (b), (c) or (d).
The plasmid pSJ1678 comprising the polynucleotide molecule (the DNA sequence) encoding a pectate lyase of the present invention has been transformed into a strain of the Escherichia coli which was deposited by the inventors according to the Budapest Treaty on the International Recognition of the Deposit of Microorganisms for the Purposes of Patent Procedure at the Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Mascheroder Weg 1b, D-38124 Braunschweig, Federal Republic of Germany, on Sep. 25, 1997 under the deposition number DSM 11788.
In a third aspect, the present invention relates to a pectate lyase which is i) a polypeptide produced by Bacillus licheniformis, ATCC 14580, or ii) a polypeptide comprising an amino acid sequence as shown in positions 28-341 of SEQ ID NO: 4, or iii) an analogue of the polypeptide defined in i) or ii) which is at least 45% homologous with said polypeptide, or iv) is derived from said polypeptide by substitution, deletion or addition of one or several amino acids, provided that the arginine in position 233, and optionally also the arginine in position 238, is conserved and the derived polypeptide is at least 42% homologous with said polypeptide, or v) is immunologically reactive with a polyclonal antibody raised against said polypeptide in purified form.
Within one aspect, the present invention provides an isolated polynucleotide molecule selected from the group consisting of (a) polynucleotide molecules encoding a polypeptide having pectate lyase activity and comprising a sequence of nucleotides as shown in SEQ ID NO: 3 from nucleotide 82 to nucleotide 1026; (b) species homologs of (a); (c) polynucleotide molecules that encode a polypeptide having pectate lyase activity that is at least 45% identical to the amino acid sequence of SEQ ID NO: 4 from amino acid residue 28 to amino acid residue 341; (d) molecules complementary to (a), (b) or (c); and (e) degenerate nucleotide sequences of (a), (b), (c) or (d).
The plasmid pSJ1678 comprising the polynucleotide molecule (the DNA sequence) encoding a pectate lyase of the present invention has been transformed into a strain of the Escherichia coli which was deposited by the inventors according to the Budapest Treaty on the International Recognition of the Deposit of Microorganisms for the Purposes of Patent Procedure at the Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Mascheroder Weg 1b, D-38124 Braunschweig, Federal Republic of Germany, on Sep. 25, 1997 under the deposition number DSM 11789.
In a fourth aspect, the present invention relates to a pectate lyase which is a polypeptide produced by a Bacillus species having the 16S rDNA sequence of SEQ ID NO: 14 or by a Bacillus species having a 16S rDNA sequence homology to SEQ ID NO: 14 higher than 97.3%; ii) a polypeptide comprising an amino acid sequence as shown in positions 181-509 of SEQ ID NO: 6, or iii) an analogue of the polypeptide defined in i) or ii) which is at least 50% homologous with said polypeptide, or iv) is derived from said polypeptide by substitution, deletion or addition of one or several amino acids, provided that the arginine in position 390, and optionally also the arginine in position 395, is conserved and the derived polypeptide is at least 44% homologous with said polypeptide, or v) is immunologically reactive with a polyclonal antibody raised against said polypeptide in purified form.
Within one aspect, the present invention provides an isolated polynucleotide molecule selected from the group consisting of (a) polynucleotide molecules encoding a polypeptide having pectate lyase activity and comprising a sequence of nucleotides as shown in SEQ ID NO: 5 from nucleotide 541 to nucleotide 1530; (b) species homologs of (a); (c) polynucleotide molecules that encode a polypeptide having pectate lyase activity that is at least 50% identical to the amino acid sequence of SEQ ID NO: 6 from amino acid residue 181 to amino acid residue 509; (d) molecules complementary to (a), (b) or (c); and (e) degenerate nucleotide sequences of (a), (b), (c) or (d).
The plasmid pSJ1678 comprising the polynucleotide molecule (the DNA sequence) encoding a pectate lyase of the present invention has been transformed into a strain of the Escherichia coli which was deposited by the inventors according to the Budapest Treaty on the International Recognition of the Deposit of Microorganisms for the Purposes of Patent Procedure at the Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Mascheroder Weg 1b, D-38124 Braunschweig, Federal Republic of Germany, on Sep. 8, 1998 under the deposition number DSM 12403.
In a fifth aspect, the present invention relates to a pectate lyase which is i) a polypeptide produced by a strain of the species Bacillus halodurans, preferably the species Bacillus sp. KJ59, DSM 12419, or ii) a polypeptide comprising an amino acid sequence as shown in positions 42-348 of SEQ ID NO: 8, or iii) an analogue of the polypeptide defined in i) or ii) which is at least 45% homologous with said polypeptide, or iv) is derived from said polypeptide by substitution, deletion or addition of one or several amino acids, provided that the arginine in position 240, and optionally also the arginine in position 245, is conserved and the derived polypeptide is at least 40% homologous with said polypeptide, or v) is immunologically reactive with a polyclonal antibody raised against said polypeptide in purified form.
The Bacillus sp. KJ59, which is believed to be a strain belonging to or at least very closely related to the known species Bacillus halodurans was deposited by the inventors according to the Budapest Treaty on the International Recognition of the Deposit of Microorganisms for the Purposes of Patent Procedure at the Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Mascheroder Weg 1b, D-38124 Braunschweig, Federal Republic of Germany, on Sep. 21 1998 under the deposition number DSM 12419.
Within one aspect, the present invention provides an isolated polynucleotide molecule selected from the group consisting of (a) polynucleotide molecules encoding a polypeptide having pectate lyase activity and comprising a sequence of nucleotides as shown in SEQ ID NO: 7 from nucleotide 124 to nucleotide 1047; (b) species homologs of (a); (c) polynucleotide molecules that encode a polypeptide having pectate lyase activity that is at least 45% identical to the amino acid sequence of SEQ ID NO: 8 from amino acid residue 42 to amino acid residue 348; (d) molecules complementary to (a), (b) or (c); and (e) degenerate nucleotide sequences of (a), (b), (c) or (d).
In a sixth aspect, the present invention relates to a pectate lyase which is a polypeptide produced by a Bacillus species having the 16S rDNA sequence of SEQ ID NO: 13 or by a Bacillus species having a 16S rDNA sequence homology to SEQ ID NO: 13 higher than 98.1%; ii) a polypeptide comprising an amino acid sequence as shown in positions 25-335 of SEQ ID NO: 10, or iii) an analogue of the polypeptide defined in i) or ii) which is at least 45% homologous with said polypeptide, or iv) is derived from said polypeptide by substitution, deletion or addition of one or several amino acids, provided that the arginine in position 227, and optionally also the argininge in position 232, is conserved and the derived polypeptide is at least 41% homologous with said polypeptide, or v) is immunologically reactive with a polyclonal antibody raised against said polypeptide in purified form.
Within one aspect, the present invention provides an isolated polynucleotide molecule selected from the group consisting of (a) polynucleotide molecules encoding a polypeptide having pectate lyase activity and comprising a sequence of nucleotides as shown in SEQ ID NO: 9 from nucleotide 73 to nucleotide 1008; (b) species homologs of (a); (c) polynucleotide molecules that encode a polypeptide having pectate lyase activity that is at least 45% identical to the amino acid sequence of SEQ ID NO: 10 from amino acid residue 25 to amino acid residue 335; (d) molecules complementary to (a), (b) or (c); and (e) degenerate nucleotide sequences of (a), (b), (c) or (d).
The plasmid pSJ1678 comprising the polynucleotide molecule (the DNA sequence) encoding a pectate lyase of the present invention has been transformed into a strain of the Escherichia coli which was deposited by the inventors according to the Budapest Treaty on the International Recognition of the Deposit of Microorganisms for the Purposes of Patent Procedure at the Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Mascheroder Weg 1b, D-38124 Braunschweig, Federal Republic of Germany, on Sep. 8, 1998 under the deposition number DSM 12404.
Within another aspect of the invention there is provided an expression vector comprising the following operably linked elements: a transcription promoter; a DNA segment selected from the group consisting of a) polynucleotide molecules encoding a polypeptide having pectate lyase activity comprising a nucleotide sequence as shown in SEQ ID NO: 1 from nucleotide 79 to nucleotide 1077, in SEQ ID NO: 3 from nucleotide 82 to nucleotide 1026, in SEQ ID NO: 5 from nucleotide 541 to nucleotide 1530, in SEQ ID NO: 7 from nucleotide 124 to nucleotide 1047 or as shown in SEQ ID NO: 9 from nucleotide 73 to nucleotide 1008, b) polynucleotide molecules encoding a polypeptide having pectate lyase activity that is at least 50% identical to the amino acid sequence of SEQ ID NO: 2 from amino acid residue 27 to amino acid residue 359, of SEQ ID NO: 4 from amino acid residue 28 to amino acid residue 341, of SEQ ID NO: 6 from amino acid residue 181 to amino acid residue 509, of SEQ ID NO: 8 from amino acid residue 42 to amino acid residue 348 or to the amino acid sequence of SEQ ID NO: 10 from amino acid residue 25 to amino acid residue 335, and (c) degenerate nucleotide sequences of (a) or (b); and a transcription terminator.
Within yet another aspect of the present invention there is provided a cultured cell into which has been introduced an expression vector as disclosed above, wherein said cell expresses the polypeptide encoded by the DNA segment.
A further aspect of the present invention provides an isolated polypeptide having pectate lyase activity selected from the group consisting of a) polypeptide molecules having pectate lyase activity and comprising an amino acid sequence as shown in SEQ ID NO: 2 from residue 27 to residue 359; b) polypeptide molecules having pectate lyase activity and which are at least 45% identical to the amino acids of SEQ ID NO: 2 from amino acid residue 27 to amino acid residue 359; c) polypeptide molecules having pectate lyase activity and comprising an amino acid sequence as shown in SEQ ID NO: 4 from residue 28 to residue 241; d) polypeptide molecules having pectate lyase activity and which are at least 45% identical to the amino acids of SEQ ID NO: 4 from amino acid residue 28 to amino acid residue 341; e) polypeptide molecules having pectate lyase activity and comprising an amino acid sequence as shown in SEQ ID NO: 6 from residue 181 to residue 509; f) polypeptide molecules having pectate lyase activity and which are at least 50% identical to the amino acids of SEQ ID NO: 6 from amino acid residue 181 to amino acid residue 509; g) polypeptide molecules having pectate lyase activity and comprising an amino acid sequence as shown in SEQ ID NO: 8 from residue 42 to residue 348; h) polypeptide molecules having pectate lyase activity and which are at least 45% identical to the amino acids of SEQ ID NO: 8 from amino acid residue 42 to amino acid residue 348; i) polypeptide molecules having pectate lyase activity and comprising an amino acid sequence as shown in SEQ ID NO: 10 from residue 25 to residue 335; k) polypeptide molecules having pectate lyase activity and which are at least 45% identical to the amino acids of SEQ ID NO: 10 from amino acid residue 25 to amino acid residue 335; and l) species homologs of a), b), c), d), e), f), g), h), i) and k).
Within another aspect of the present invention there is provided a composition comprising a purified pectate lyase according to the invention in combination with other polypeptides having enzymatic activity.
Within another aspect of the present invention there are provided methods for producing a polypeptide according to the invention comprising culturing a cell into which has been introduced an expression vector as disclosed above, whereby said cell expresses a polypeptide encoded by the DNA segment and recovering the polypeptide.
The novel pectate lyase enzymes of the present invention are useful for the treatment of cellulosic material, especially cellulose-containing fiber, yarn, woven or non-woven fabric, treatment of mechanical paper-making pulps or recycled waste paper, and for retting of fibers. The treatment can be carried out during the processing of cellulosic material into a material ready for garment manufacture or fabric manufacture, e.g. in the desizing or scouring step; or during industrial or household laundering of such fabric or garment.
Accordingly, in further aspects the present invention relates to a detergent composition comprising an enzyme having substantial pectate lyase activity; and to use of the enzyme of the invention for the treatment of cellulose-containing fibers, yarn, woven or non-woven fabric.
The pectate lyases of the invention are very effective for use in an enzymatic scouring process in the preparation of cellulosic material e.g. for proper response in subsequent dyeing operations. Further, it is contemplated that detergent compositions comprising the novel pectate lyases are capable of removing or bleaching certain soils or stains present on laundry, especially soils and spots resulting from galactan or arabinogalactan containing food, plants, and the like. It is also contemplated that treatment with detergent compositions comprising the novel enzyme can prevent binding of certain soils to the cellulosic material. The enzymes of the invention are also useful as ingredients in hard surface cleaning compositions having the effect of removing or assisting in removing certain soils or stains from hard surfaces in need of cleaning.